Looking at the stats and requirements, the shaku is ridiculous. No one would want to sacrfice a better weapon (the ninkondi) AND a forma to make this. However, after some brainstorming and a few calculations i've found myself a good build for high armored enemy types. Please keep in mind that this is my first blog, so your advices will be greatly recieved. Here's the build.

Stance : Atlantis Vulcan

Utility mods : Maiming Strike ; Berserker ; Pressure Point ; Shattering Impact

Damage mods : Virulent Scourge ; Voltaic Strike ; Fever Strike ; Shocking Touch

The stance is pretty obvious as it is the only one available. Maiming Strike provides 90% ADDITIVE crit chance on slide attacks for a total of 9>7.5% crit chance. This, combined with the fact that the stance deals three hits on slide attacks should give you a full berserker bonus in a single button press. Shattering reduces 6 BASE armor from each hit, more about this will be covered later.

Now for the calculations. The combined damage mods will yield 300% corrosive damage. This makes the damage to be 75% corrosive and 25% impact (notice that if i had put Primed Heavy Trauma and Collision Force instead of Fever Strike and Shocking touch, only about 24% of the damage is corrosive). The combined dual stat mods will yield 55% status chance. So for the corrosive armor reduction we have 75%x55%x25%=10.3% current armor reduction. Combining it with shattering strike, we have:

Armor(#)=Armor(#-1)-6-Armor(#-1)x0.103 ; # = number of hits

Using this formula, a heavy gunner (base armor 500) will be completely stripped of its armor after 21 hits. Also, since the formula for enemy armor is: 

Base Armor × ( 1 + ( Current Level − Base Level )1.75 × 0.005 ).

So even level 100 Heavy gunners (armor 7332.33) will also be stripped off in 21 hits.

Well 21 hits is a lot. However the Blazing Vortex combo has 20 hits in its entirety. The combo is also is easy to pull off (just hold E till the guy jumps, then press E again) so having berserker won't be a problem. 

To summarize, we can destroy any kind of enemies' armor within just one combo set (which is quick considering shaku's attack speed and berserker).

Note : This is all purely theoretical and i can't test this because my laptop is shitty and my PC is at home (i'm currently studying away), so i would really appreciate it if somone could do that for me.

Note #2 : this build in ninkondi is also good (replacing the shattering impact with another dual element mods) however it can't reach zero due to the nature of corrosive procs. 10% of 8k is still a lot of armor, so i'd rather use shaku instead.